php-doc-en/reference/mysqli/functions/mysqli-connect.xml

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<refentry xml:id="function.mysqli-connect" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysqli_connect</refname>
  <refname>mysqli->__construct()</refname>
  <refpurpose>Open a new connection to the MySQL server</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>Procedural style</para>
  <methodsynopsis>
   <type>mysqli</type><methodname>mysqli_connect</methodname>
   <methodparam choice='opt'><type>string</type><parameter>host</parameter></methodparam>
   <methodparam choice='opt'><type>string</type><parameter>username</parameter></methodparam>
   <methodparam choice='opt'><type>string</type><parameter>passwd</parameter></methodparam>
   <methodparam choice='opt'><type>string</type><parameter>dbname</parameter></methodparam>
   <methodparam choice='opt'><type>int</type><parameter>port</parameter></methodparam>
   <methodparam choice='opt'><type>string</type><parameter>socket</parameter></methodparam>
  </methodsynopsis>
  <para>Object oriented style (constructor):</para>
  <classsynopsis>
  <ooclass><classname>mysqli</classname></ooclass>
   <constructorsynopsis>
    <methodname>__construct</methodname>
    <methodparam choice='opt'><type>string</type><parameter>host</parameter></methodparam>
    <methodparam choice='opt'><type>string</type><parameter>username</parameter></methodparam>
    <methodparam choice='opt'><type>string</type><parameter>passwd</parameter></methodparam>
    <methodparam choice='opt'><type>string</type><parameter>dbname</parameter></methodparam>
    <methodparam choice='opt'><type>int</type><parameter>port</parameter></methodparam>
    <methodparam choice='opt'><type>string</type><parameter>socket</parameter></methodparam>
   </constructorsynopsis>
  </classsynopsis>
  <para>
   Opens a connection to the MySQL Server running on.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>host</parameter></term>
     <listitem>
      <para>
       Can be either a host name or an IP address. Passing the &null; value
       or the string "localhost" to this parameter, the local host is
       assumed. When possible, pipes will be used instead of the TCP/IP
       protocol.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>username</parameter></term>
     <listitem>
      <para>
       The MySQL user name.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>passwd</parameter></term>
     <listitem>
      <para>
       If not provided or &null;, the MySQL server will attempt to authenticate
       the user against those user records which have no password only. This
       allows one username to be used with different permissions (depending
       on if a password as provided or not).
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>dbname</parameter></term>
     <listitem>
      <para>
       If provided will specify the default database to be used when
       performing queries.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>port</parameter></term>
     <listitem>
      <para>
       Specifies the port number to attempt to connect to the MySQL server.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>socket</parameter></term>
     <listitem>
      <para>
       Specifies the socket or named pipe that should be used.
      </para>
      <note>
       <para>
        Specifying the <parameter>socket</parameter> parameter will not
        explicitly determine the type of connection to be used when
        connecting to the MySQL server. How the connection is made to the
        MySQL database is determined by the <parameter>host</parameter>
        parameter.
       </para>
      </note>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a object which represents the connection to a MySQL Server or
   &false; if the connection failed.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title>Object oriented style</title>
   <programlisting role="php">
<![CDATA[
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

printf("Host information: %s\n", $mysqli->host_info);

/* close connection */
$mysqli->close();
?>
]]>
  </programlisting>
  </example>
  <example>
   <title>Procedural style</title>
   <programlisting role="php">
<![CDATA[
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");

/* check connection */
if (!$link) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

printf("Host information: %s\n", mysqli_get_host_info($link));

/* close connection */
mysqli_close($link);
?>
]]>
   </programlisting>
  </example>
  &example.outputs;
  <screen>
<![CDATA[
Host information: Localhost via UNIX socket
]]>
  </screen>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    Error "Can't create TCP/IP socket (10106)" usually means that the <link
    linkend="ini.variables-order">variables_order</link> configure directive
    doesn't contain character <literal>E</literal>. On Windows, if the
    environment is not copied the <literal>SYSTEMROOT</literal> environment
    variable won't be available and PHP will have problems loading Winsock.
   </para>
  </note>
 </refsect1>

</refentry>

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